Cornforth Theodore W, Long Anthony D
Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92697-2525, USA.
Genet Res. 2003 Oct;82(2):139-49. doi: 10.1017/s0016672303006396.
This paper examines the properties of likelihood maps generated by interval mapping (IM) and composite interval mapping (CIM), two widely used methods for detecting quantitative trait loci (QTLs). We evaluate the usefulness of interpretations of entire maps, rather than only evaluating summary statistics that consider isolated features of maps. A simulation study was performed in which traits with varying genetic architectures, including 20-40 QTLs per chromosome, were examined with both IM and CIM under different marker densities and sample sizes. IM was found to be an unreliable tool for precise estimation of the number and locations of individual QTLs, although it has greater power for simply detecting the presence of QTLs than CIM. The ability of CIM to resolve the correct number of QTLs and to estimate their locations correctly is good if there are three or fewer QTLs per 100 centiMorgans, but can lead to erroneous inferences for more complex architectures. When the underlying genetic architecture of a trait consists of several QTLs with randomly distributed effects and locations likelihood profiles were often indicative of a few underlying genes of large effect. Studies that have detected more than a few QTLs per chromosome should be interpreted with caution.
本文研究了区间作图（IM）和复合区间作图（CIM）生成的似然图谱的特性，这两种方法是检测数量性状基因座（QTL）广泛使用的方法。我们评估了对整个图谱进行解读的有用性，而不是仅评估考虑图谱孤立特征的汇总统计量。进行了一项模拟研究，其中在不同的标记密度和样本量下，用IM和CIM检验了具有不同遗传结构的性状，包括每条染色体有20 - 40个QTL。尽管IM在简单检测QTL的存在方面比CIM具有更强的功效，但它被发现是一种用于精确估计单个QTL数量和位置的不可靠工具。如果每100厘摩有三个或更少的QTL，CIM分辨正确QTL数量并正确估计其位置的能力良好，但对于更复杂的结构可能会导致错误的推断。当性状的潜在遗传结构由几个具有随机分布效应和位置的QTL组成时，似然分布往往表明存在少数几个具有大效应的潜在基因。对于每条染色体检测到多个QTL的研究应谨慎解读。
